June 13, 2011

Quitting Smoking Without Gaining Weight

(Ivanhoe Newswire) -- Smokers may die young, but they also die thinner than non-smokers. Scientists have discovered exactly how nicotine suppresses the appetite, and these findings suggest it might be possible to develop a drug that would help smokers and non-smokers stay thin.

Nicotine activates a small set of neurons in a part of the hypothalamus that tells the body it's had enough to eat. Nicotine accomplishes this by activating a different set of receptors on the surface of neurons aside from those that trigger a tobacco craving.

"Unfortunately, smoking does keep weight off," Marina Picciotto, the Charles B.G. Murphy Professor of Psychiatry at Yale School of Medicine, professor of neurobiology and pharmacology and senior author of the paper, was quoted as saying.

"Many people say they won't quit smoking because they'll gain weight. Ultimately, we would like to help people maintain their body weight when they kick the habit and perhaps help non-smokers who are struggling with obesity."

Nicotinic acetylcholine receptors are the primary targets of nicotine. Yann Mineur, as associate research scientist in Picciotto's lab, was investigating a potential drug for depression that acts upon these receptors. He noticed that mice given the drug ate less than those not on the medication.

In a variety of experiments, the researchers found that the experimental drug activated a specific type of nicotine receptor, which in turn activated the subset of neurons in the hypothalamus, called pro-opiomelanocortin or POMC cells. The team also found that when subjected to nicotine, mice lacking the POMC pathway did not lose weight, unlike mice with the pathway intact. They also showed that these receptors were of a different type than those known to trigger tobacco craving in smokers.

"This suggests it is possible to get the effect of appetite suppression without also triggering the brain's reward centers," Picciotto said.

SOURCE: Science, published online June 10, 2011